I remember hearing about a story in the Gemara where a "surgery" was done on someone who was very overweight, and they ended up removing an amount of fat that doctors nowadays cant do.
Does anyone know where in the gemara this is found?
I believe the story you’re looking for is in Bava Metzi’a 83b:
אשקיוהו סמא דשינתא ועיילוהו לביתא דשישא וקרעו לכריסיה הוו מפקו מיניה דיקולי דיקולי דתרבא
They gave him a sedative to drink, and they brought him into a house of marble, and cut open his belly. They removed baskets upon baskets of fat from it.